Interfacial temperature difference driven water diffuse through nitrogen gas and nucleation on the nanostructured surfaces: Evolution of vapor condensation and theory prediction

The atomic nucleation and steady condensation of water on both smooth and textured surfaces are thoroughly examined in this study using a series of molecular dynamics simulations. A comparable nucleation progression occurs across different temperature differences and nitrogen densities on smooth surfaces. The introduction of non-condensable gas leads to the formation of an extra diffusion layer, resulting in a linear rise in water density along the z-direction. Consequently, the corresponding steady-state condensation rate (J) decreases with the increase in nitrogen density. The tracking of water molecule trajectories verified that incorporating nanopillars on smooth surfaces promotes the collision of solid–vapor, thereby decreasing the probability of molecules reverting back to the gas phase after collision. These factors cumulatively contribute to an elevation in nucleation density and the steady-state condensation rate J. In the condensate, a greater concentration of hydrogen bonds near the nanostructure surface is observed compared to smooth surfaces, enhancing the energy transport across the solid–liquid interface. Additionally, the textured surface expands the area of solid–liquid interaction. Ultimately, although high-temperature vapor molecules accumulate more quickly on the textured subcooled surface, the condensate demonstrates a lower average temperature compared to that on the smooth surface. Combining Schrage relation and Stefan's law, a linear correlation between the steady-state condensation rate and temperature difference (ΔT) at the gas–liquid interface is predicted on the nanostructure surfaces in the presence of non-condensable nitrogen molecules.